Waterproof paper board



Patented Sept. 25, 1923.

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wnrnarnoor No Drawing.

To all whom it may concern.

Be it known that I, ALBERT L. CLAPP, a citizen of the United States, residin at Danvers, in the county of Essex and tate of Massachusetts, have invented new and useful Improvements in Waterproof Paper Board, of which the following is a speclfication.

The object of this invention is to provide a paper board or. box board which is highly waterproof and which has a smooth glassy exterior finish at least on one face and is adapted for use in the manufacture of cartons or boxes so that the contents thereof may be maintained in the same condition in which they were introduced into the container or box and without material gain or loss in moisture.

A further object of the invention is to rovide a recess by which the paper or ard may be produced on a paper machine continuously.

In carrying out m invention, while it is possible to form the board of a single layer of water roof material, I preferably form it in a p urality of layers, the outer or bottom layer of which is formed of the waterproof material.

As the waterproofing agent, I employ Montan wax, crushed or owdered into a finely divided state, which is mixed with the paper stock in the beating engine. This alone cannot be precipitated by the use of usual precipitating agents, such as alum, so that, in order to produce a more or less flocculent precipitate when a suitable agent is emplo ed, 1 add to the fibrous stock during the ating o eration a certain amount of fine hydrated ime,Ca(OH-),. 'Apparently a slight chemical reaction results when the lime is brought intocontact with the Montan wax, leaving a large proportion of the Montan wax in a free state, but this chemical reaction is sufiicient to cause the Montan wax and the precipitate to be thrown down together on the fiber when a precipitant is added. I have found that by the addition of lime there is a coagulating action and a desirable flocculency of the precipitate is secured after the reci itating agent is added to the furnis ducing a waterproof material, any suitable fibrous materia is placed in the beater with sufiicient warm water to ensure its circulation. I may, for example, utilize chemical or ground wood pulp, mixed papers or other pro= rarna Leeann.

Application filed June 18,1922. Berta! No. 567,752.

fibrous material used in paper making. Thus may place in the beater 100 arts by welght of mixed pa ers and water, eatedto a temperature 0 approximately 110 to 120 F., in sufiicient quantity to ensure the circulation of the stock, and at the same t me I add 2 parts by weight of finely dlvlded calcium hydroxide. By uslng warm water the chemical reaction of the lime and the Montan wax is increased, thereby increasin the volume of the preclpitate. With t e roll adjusted down to the bed (plate, the contents of the beater are subjecte to hard beating for about 15 minutes until the paper is dlsintegrated and the fibers separated, and the lime in suspension is thoroughly mixed with the fibrous mass. I then add a proximately 20 parts by weight of pow ered Montan wax. Preferably this ingredient is in the state of fine subdivision so that it will pass through a sieve of about 40 to mesh. With the roll still ad'usted down to the bed plate, the contents o the beater are beaten hard for about 30 minutes, the water being maintained at about the same temperature as before. This beating operation effectively distributes the Montan wax throughout the pulpy' mass and continues the further disinte ration of the fibers. I now add sufiicient a um to effect the, precipitation of the lime and Montan wax, and, adjusting the roll from the bed late so that it will not cut the fiber but brus the same, I continue the beater in operation for approximately 30 minutes. A pulp or stock 1s now produced in which the Montan wax is precipitated on or fixed to the fibers to a greater or less extent and may be formed into a web without loss of the Montan wax.

While the furnish thus described is eminently satisfactroy for many purposes, I find that still better results ma be secured by addin to the beater stoch, previous to the ad it1on of the precipitating agent, rosin size or silicate of soda or both. For exam le, after the Montan wax has been added to the beater contents and the stock is beaten for 30 minutes, I may add 5 parts by weight of sodium silicate and 5 arts by wei ht of sodium resinate, after w ich the stoc is beaten for 15 minutes. Thereafter I add 10 parts by weightof alum, and, adjusting the roll so that it will brush the fibers, continue the operation of the beater for approximately 30 minutes. By the ad-= are ' precipitate are increased and the Montan.

dition of silicate of soda or rosin size or both, the volume and the flocculency of the wax 1s caused to adhere to the fibers. From this stock a sheet is formed by means of any suitable paper-makin macl nne, such as a cylinder machine, an 1s dried on the usual drier rolls. Preferably these rolls are heated to a temperature at which the articles of Montan wax are softened or me ted so as to permeate any open interstices in the sheet and to fuse to ether or coalesce. After bein dried, the sheet is preferably calendered by calender rolls, as a result of which it resents a smooth glassy exterior surface. he sheet practically does not absorb water to any appreciable extent and 1s substantially water and moisture proof. The Montan Wax is present in such small proportions that the sheet may be bent or creased without readily cracking or break- %Vhile a sheet formed of a single layer of waterproof material as thus described may be utilized for many purposes, I preferably form a composite sheet of two or more adherent plies by the use of a multi-cylinder machine. In making a two-ply or a three-' ply board, for example, the additional layers or laminations may be formed of any suitable fibrous stock. In producing a three-ply board which may be bent or creased without breaking and thus be adapted 'for use in the manufacture of boxes or cartons, the top layer or lamination may be produced from a furnish consisting of approximately 30 parts by weight of bleached sulphite, 40 parts by weight of bookcuttings and 30 arts by weight of news print. If this irnish be employed, it, together with sulficient water to ensure its circulation, is beaten for approximately 30 to 45 minutes hard beating. The furnish for the center layer or layersmay consist of mixed news paper, in which case it is subjected to hard beating for about 45 minutes more or less.

It is quite evident that any suitable number ofcylinders may be utilized for these beater stocks in formingthe web. If, for example, a six-cylinder machine is used, the waterproof material may be placed in the vat of one cylinder, the stock of mixed sulphite, book cuttings and news in one cylinder, and the other stock placed in the vats of the remaining cylinders. In such case, assuming'that the caliper of the composite sheet is 21-25 points, the bottom layer may be 3-5 points, the top layer 3-5 points and the intermediate la er 15 points. Where a composite sheet is thus formed in a continuous sheet or web, the web is passed through the usual dry end of the'machine, and then through calender rolls as before described.

While other hard gums or bitumens may be used in lieu of Montan wax, the latter reeaeee possesses certain decided advantages. That is to say, it has a relatively low melting point, a short melting-point lag, and when melted has a high degree of penetrability,

In the production of the waterproof material in the beater, I regard it as exceedingly desirable that the beating should be con-' tinued for a substantial time after the precipitating agent has been added to the stock. I have found that the best results are secured by continuing the beating or brushing for at least 25 to 30 minutes.

It has heretofore been proposed to add ilsonite or other hard friable asphalts or itumens to paper stock in the formation of a sheet, but the sheets thus produced are decidedly unlike one produced as herein described. By the addition of the calcium hydroxide to the Montan wax and the employment of a precipitating agent either with or without sodium silicate, rosin size or the like, I am able to secure a more even distribution of the Montan wax through the pulpy mass and its attachment to the individual fibers due to the voluminous and flocculent precipitate formed. It is important that the precipitate as it is thrown down should be in a flocculent ,coagulated condition, and, as previously stated, this is increased by the use of lime or its equivalent, and metallicsalt precipitating agent.

By the production of a composite sheet having the water-proof and moisture-proof bottom layer, it is possibleto manufacture the cartons with this layer or lining, as it were, on the inner surface of the box walls so that the outer walls may receive the printing or advertising matter which is usually placed on such cartons.

By the formation of a waterproof ply or layer, as herein first described, the composite sheet is flat and does not curl or blister. This is due to the flocculent precipitate and to the increased or prolonged beating after the precipitating agent has been added;

One of the advantages of the improvements herein described is that the waterproof layer of the composite sheet is so ighly waterproof that it can be formed in a very thin layer, .j-even .002 to .003 inch,- and thus enable one to roduce a waterproofed board at very slig t expense.

What I claim is 1. A process of making waterproof paper or box board, which comprises beating finely divided Montan wax into a ul y mass of cellulose fiber containing finely divided calcium hydroxide, adding a precipitating agent, and forming the pulpy mass into a sheet or web.

2. A process of making waterproofpaper or box board, which comprises beating a mass of cellulose fiber and finely divided lime in warm water, adding finely divided Montan wax to and distributing the same throughout into a web or sheet.

4. A process of making waterproof paper or box board, comprising ting cellulose fiber (100 parts) and lime (2 parts) in warm water; adding Montan wax (20 parts) to and distributing it throughout the pulpy mass; mixin ros1n size and silicate of soda (5 parts of each) with said mass; adding a precipitating a ent to and distributing the same throug out the mass, and then forming the pulp into a web or sheet.

5. A'process of making waterproof paper or box board, which comprises beating finely divided Montan wax into a ul y mass of cellulose fiber containing finely divided calcium hydroxide, adding a precipitating agent, forming the pulpy mass into a sheet or web, anddrying said sheet at a temperature sufficient to flux the contained Montan wax.

6. A process of making waterproof paper or box board, which comprises beating finely divided Montan wax into apulpy mass of cellulose fiber containing finely divided calcium hydroxide, adding a precipitating agent, forming the pulpy mass into a sheet or web, drying said sheet at a temperature sufficient to flux the contained Montan wax, and finely calendaring the sheet to glaze the surface thereof. 7

7. A process of making waterproof paper or box board, which comprises beating a mass of cellulose fiber and finely divided lime in warm water, adding finely divided Montan wax to and distributing the same throughout the mass, adding a precipitating agent, then forming the pulpy mass into a sheet or web, and dryin said sheet at a temperature sufficient to ux the contained Montan wax.

8. A process of making waterproof aner or box board, comprising beatin cel ulose fiber (100 parts) and lime (2 parts in warm water; adding Montan wax (20 parts) to and distributing it throughout the pulpy mass; adding alum to cause the precipitation of a fiocculent precipitate, forming the mass into a web or sheet; progressively drying said sheet at a temperature sufiicient to flux the contained Montan wax, and finally calendering the sheet to glaze the surface thereof.

9. A process of forming a composite sheet having an exterior waterproof ply or layer, which comprises beating Montan wax mto a mass of cellulose fibers and lime, and adding alum to thereby precipitate a coagulent and fiocculent preclpitate on the fibers; pulping a second mass of paper stock, then bringing webs of such masses into adherent facial contact, and felting and drying the sheet thus formed.

10. A glazed-surface waterproof paper or box board comprising felted cellulose fiber, Montan wax and an insoluble flocculent precipitate.

11. A composite paper or box board, comprising a layer of felted fiber, and an adherent exterior thin highly-waterproof layer of fiber, Montan wax and a voluminous flocculent recipitate.

12. composite paper or box board, comprising a layer of felted fiber, and an adherent exterior thin highly-waterproof layer of fiber, Montan wax and a voluminous flocculent precipitate, said layer not exceeding two to three one-thousandths of an inch in thickness.

In testimony whereof I have aflixed my signature.

ALBERT L. CLAP P. 

